The evaporator coil in a central air conditioning system is an ideal location for bacteria and other microorganisms to grow. Some of them are pathogens while others just add a foul smell to the air. Moisture in the air, which tends to condense on the cool surface of the evaporator coil, is usually captured in a drip pan which is not only equipped with a drain but also designed so that the air flowing past the evaporator coil picks up moisture accumulated in the pan. Notwithstanding these features, the pan does retain a certain amount of water. Conditions are such that microorganisms present in the incoming air may lodge and grow in the moist pan and on the coil surface. There is always the chance that bacteria, viruses, yeast mold, mildew and their various spores will get into the air stream flowing past the evaporator coil and its drip pan.
The object of this invention is to provide a means for irradiating, with ultraviolet light, surfaces of the evaporator coil and drip pan in such a way to both kill and prevent any buildup of pathogens thereon.
In accordance with the present invention, the irradiating means comprises an elongated ultraviolet lamp which is mounted centrally relative to the evaporator coil surfaces, so that its light strikes them, and transversely to the flow path of the air as it passes through the evaporator. Shielding the lamp is a quartz tube which envelopes it.
In the preferred embodiment, one end of the quartz tube is secured, using a sleeve which projects perpendicularly from a flat base, to a sidewall of a sheet metal container surrounding the evaporator coil shell. Slip-fitted into the outwardly protruding sleeve, the quartz tube extends into the shell itself through concentric holes formed in it and in the sidewall. These holes measure, by way of example, 1 inch and 3 inches in diameter, respectively. In a conventional xe2x80x9cAxe2x80x9d frame-type evaporator coil, the quartz tube, with the ultraviolet lamp inserted therewith in, is positioned midway between the legs of the xe2x80x9cAxe2x80x9d frame.